The present disclosure relates to an image-forming device, such as a photocopier, printer, or fax, or an all-in-one device combining the functions thereof; and to a light scanning device employed in an image-forming device; and relates in particular to an image-forming device for scanned exposure of the surface of an image carrier, forming a latent image on the image carrier.
In a conventional image-forming device, a light scanning device performs a scanned exposure of the surface of an image carrier, forming a latent image on the image carrier. Such a light scanning device is extremely sensitive to particulate contaminants such as dust or dirt, and when particulate contaminants become deposited on optical components, such as lenses or mirrors, in the interior of the unit of the light scanning device, the beam of the light may become blocked by the particulate contaminants, reducing the amount of the light, and giving rise to image defects such as streaks and density irregularities. In order to prevent infiltration of such particulate contaminants into the interior of the unit, the light scanning device unit has a highly hermetic design. However, in order to form a latent image on the image carrier, the unit must have an opening through which the light beam is output onto the image carrier, and accordingly there is a risk of particulate contaminants infiltrating into the unit through the opening.
Accordingly, in the prior art, techniques for preventing infiltration of particulate contaminants into the interior of the unit through the opening for output of a light beam are known. In an image-forming device according to a first related art, a shutter member is arranged nearby the output window that outputs the light beam for forming a latent image on the image carrier. The shutter member can be moved by an actuating mechanism capable of opening and shutting the output window; and, when a latent image is formed on the image carrier or at other times of image formation, opens the output window and forms a latent image on the image carrier. The actuating mechanism operates in association with a cover member that opens and shuts the inside of the device chassis. When maintenance is performed, or the image carrier or another component disposed inside the device chassis is replaced, an operation is performed to open the cover member, whereupon the shutter member shuts the output window using the actuating mechanism. Doing this makes it difficult for toner, particulate contaminants, or the like to enter inside the light scanning device through the output window when the cover member is open.
Normally, in order to perform scanned exposure of the light beam over the image carrier, a rotating polygonal mirror for deflecting the light beam is caused to rotate at high speed, and the bearing section of the motor that drives the rotation of the rotating polygonal mirror emits heat. Moreover, electrical control components on the circuit board, such as the drive circuit for controlling driving of the motor, also emit heat. The heat generated by the motor bearing section and the electrical control components becomes trapped inside the light scanning device, and the housing reaches high temperature. When the light scanning device reaches high temperature, there is a risk that optical components such as lenses and mirrors will experience heat deformation. Heat deformation of optical components in turn poses a risk of an inability to form a good latent image on the surface of the image carrier.